Device for the fabrication of a tire reinforcement, suitable for tires of large width

ABSTRACT

Device for fabricating a tire reinforcement by laying a cord  4  on a core  1.  An arm  131  is mounted on a carriage  130,  which is itself mounted on a rail  132  in such manner that it can slide parallel relative to the rotation axis of the core  1.

FIELD OF THE INVENTION

[0001] The present invention relates to the manufacture of tires. Moreprecisely, it concerns the positioning of cords to constitute a tirereinforcement. More particularly, it proposes means suitable inparticular for fabricating such reinforcement on a form close to oridentical with the shape of the tire's internal cavity, i.e. one havingan essentially toroidal shape, which supports the tire blank during itsfabrication.

BACKGROUND OF THE INVENTION

[0002] In this technical field processes and equipment are already knownwhich enable the fabrication of tire reinforcements to be integratedwith the assembly of the tire itself. This means that rather than havingrecourse to semi-finished products such as reinforcement plies, one ormore reinforcements are made in situ, as the tire is being fabricated,and from a cord spool. Among the processes and equipment, the solutiondescribed in patent application EP 1 122 057 is well suited to theproduction of carcass reinforcements on a rigid core whose outer surfacecorresponds essentially to the shape of the internal cavity of the finaltire. The document describes a device in which the cord intended to forma carcass reinforcement is positioned in contiguous arcs on a rigid coreby a mechanism having at least two arms arranged in cascade, whichundergo a back and forth movement around the core so as to put in place,progressively and in a contiguous manner, an arc each time it moves oneway and an arc each time it moves the other way, with pressing elementsappropriate for applying the ends of the arcs as they are formed on therigid core. The core has previously been covered with uncured rubber inaccordance with the structure of the tire, which has the advantageousproperty of allowing the arcs to be stuck on and kept in placesufficiently well at least for the purposes of fabrication.

[0003] The prior art includes several other devices with one or morearms which undergo alternating movements to transport an eyelet (orother cord laying element with a similar function) from one side to theother of the form serving as the build-up support for a tire. Referencecan be made to patent applications EP 0 962 304, EP 1 231 049 and EP 1231 050.

[0004] If it is desired to construct a device that can fabricate tiresof very large width, it may be necessary to have equipment whose radialdimension is accordingly large relative to the build-up form, inparticular of a size that can become considerably larger than for achain device such as that described in patent application EP 0 580 055.

SUMMARY OF THE INVENTION

[0005] One object of the present invention is to increase the capacityof devices designed on the principle of one or more arms which undergoalternating movements in order to build up tires of large width, withoutmaking the devices too heavy and while keeping them as compact aspossible.

[0006] This and other objects are attained in accordance with one aspectof the invention directed to a device for fabricating a tirereinforcement, the device being designed to produce a reinforcementformed from a cord. The device comprises a frame and is intended for usein cooperation with an essentially toroidal form mounted on the frame sothat it can rotate about a rotation axis, on which the reinforcement isbuilt up progressively by laying arcs of the cord along a trajectorydesired for the cord at the surface of the form. A cord laying elementis provided through which the cord can slide. An actuation mechanismcomprises at least one arm on which the cord laying element is mounteddirectly or indirectly, the actuation mechanism being designed totransport the cord laying element in a cyclic, back and forth movement,and which moves it in successive cycles close to each of the endsdesired for the cord in the trajectory. Pressing elements close to eachend of the trajectory are included for applying the cord onto the format least at the ends. The actuation mechanism is mounted on the framevia a support which is itself mounted on means that allow a degree offreedom relative to the frame, which means allow a parallel movementrelative to a plane tangent to a cylinder coaxial to the rotation axisof the form.

[0007] An advantage of this design is that it provides the actuationmechanism with an additional degree of freedom by the functionaltransverse translation of a support on which it is mounted, and in thisway increases the ability to lay cord in widths parallel to the rotationaxis of the tire building form, without any substantial increase of theradial dimension of the device.

[0008] The invention can be used with numerous reinforcement cord layingmechanisms, among the known mechanisms particularly those withalternating arm(s) described in the patent applications cited earlier,or even that described in the patent application filed on the same dayby the same applicants and having the title “Device for the fabricationof a tire reinforcement, having multiple positioning arms which undergoa movement guided by a cam follower sliding in a slot”.

[0009] Two example applications are given below: an example in which theactuation mechanism comprises a single oscillating arm at whose end thecord laying element is mounted directly. The second example shows anactuation mechanism comprising multiple oscillating arms: the actuationmechanism comprises a main arm mounted at the end of two auxiliary arms,and the cord laying element is mounted directly at the end of the mainarm. Of course, these examples are not limiting. In the above examples,because they are all directed to the manufacture of a radial tire, saidmeans allowing a degree of freedom provide for a movement parallel tothe rotation axis of the form, this feature being not limiting the scopeof the invention.

[0010] The reader is invited to consult in greater detail, in particularfor example patent application EP 1 122 057, because the tirefabrication process implemented in the present application is identicalto that of the application. The device is intended for use with amotorization system that controls in synchronism the rotation of theform, the actuation mechanism and the pressing elements. In addition,the present invention uses the pressing elements described in patentapplication EP 1 122 057 (an assembly comprising a hammer and a fork),to allow the formation of a loop with the reinforcing cord and to applythe loop against the core.

[0011] Before embarking on a detailed description of the new means ofactuating the cord laying element, a few useful points will be recalled.

[0012] Note, first, that as in the patent application E 1 122 057already cited, the term “cord” is of course used in an entirely generalsense, which encompasses a monofilament, a multifilament, an assemblysuch as a cable or yarn, or a small number of cables or yarns groupedtogether, and this regardless of the nature of the material, and thatthe “cord” may or may not be pre-coated with rubber. In the present textthe term “arc” is used to denote a section of cord extending from aparticular point to another in the reinforcement. The totality of thesearcs arranged all around the tire builds up the reinforcement itself. Anarc in the sense defined here can be part of a carcass, or a crownreinforcement, or any other type of reinforcement. These arcs may beindividualized by cutting the cord while positioning it, or they may allbe interconnected in the final reinforcement, for example by loops.

[0013] Basically, the invention relates to the continuous laying of areinforcing cord in a configuration as close as possible to itsconfiguration in the final product. The cord is fed in as required by asuitable distributor comprising for example a cord spool and ifnecessary a device to control the tension of the cord reeled off thespool. The device for fabricating a reinforcement from a single cordcooperates with a form (rigid core or reinforced membrane) on which thetire is built up. It is of little importance whether the reinforcementis fabricated in several successive rotations of the form in front ofthe cord laying elements described, with or without cutting of the cordbetween successive rotations.

[0014] When positions, directions or senses are defined using the words“radially, axially, circumferentially”, or when radii are mentioned,these terms relate to the core on which the tire is being built up or tothe tire itself, which amounts to the same thing. The referencegeometrical axis is the rotation axis of the form.

[0015] In addition, the cord laying elements described here also make itpossible to produce a reinforcement, for example a carcassreinforcement, with variable spacing of the cord. “Spacing” isunderstood to mean the distance comprising the interval between twoadjacent cords plus the diameter of the cord. It is well known that fora carcass reinforcement the interval between cords varies depending onthe radius at which it is measured. It is not that variation which isreferred to here, but a spacing variation at a given radius. To producethis it is sufficient, without changing the working rate of the cordlaying element, to vary the form rotation speed in accordance with anyappropriate law. This gives a tire whose carcass reinforcement cords,for example in the case of a radial carcass, are arranged according to acontrolled spacing variation for a given radial position.

[0016] Finally, the single or multiple arm(s) cause(s) the cord layingelement to undergo movement essentially confined to a plane—hereinaftercalled the movement plane—perpendicular to the geometrical rotation axisof the arm(s). In certain particular implementations of the invention,as in the patent application EP 1 122 057 cited earlier, the movementplane is itself subject to a movement with a functional role, as willbecome apparent below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The remainder of the description, which refers to the followingfigures, makes clear all aspects of the invention:

[0018]FIG. 1 is a schematic perspective view of a first embodiment of adevice according to the invention;

[0019]FIG. 2 represents successive stages in the operation of the firstembodiment;

[0020]FIG. 3 is a schematic perspective view of a second embodiment of adevice according to the invention;

[0021]FIG. 4 represents successive stages in the operation of the secondembodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

[0022] In FIG. 1 (and indeed in all the examples described, althoughthis is not limiting), the form is a core 1 (rigid and capable ofdisassembly) which defines the geometry of the internal surface of thetire. This is coated with rubber 10 (see FIG. 2), for example with alayer of gas-impermeable rubber based on butyl rubber and a layer ofrubber that ensures the anchoring of the carcass cords on the coreduring fabrication and then their embedding within the vulcanized tire.The rubber 10 covering the core 1 enables a cord 4 to be retained on thecore 1 as it is laid, by a sticking effect. Of course, the core 1 isdriven in rotation by any appropriate means (not shown).

[0023]FIG. 1 shows an actuation mechanism 3 with a single arm similar tothat described in patent application EP 1 231 049. A single arm 131 canbe seen, mounted on a carriage 130. This carriage 130 constitutes asupport carrying the actuation mechanism, here consisting of the singlearm 131. The carriage 130 is mounted to slide on a rail 132. Thecarriage 130 comprises a foot 134 to which a rod 138 is articulated. Therod 138 is also articulated to a crank 137 driven in rotation by a motor136. The motor's rotation movement does not reverse; of course, thedevice's operation rate is proportional to the rotation speed of themotor 136. To operate the device at a constant rate, i.e. so that aconstant number of cord arcs is laid in unit time, the motor 136 canturn at constant speed (although this is not obligatory). This issymbolized in the drawing by an arrow F1 pointing in only one direction.The carriage 130 undergoes alternating translational movements guided bythe rail 132. The amplitude of those movements depends on the size ofthe crank 137, which can be made adjustable (not shown).

[0024] The movement of the arm 131 is controlled by a motor 135 whichdrives a splined shaft 133. The splined shaft 133 passes through thecarriage 130. The rotation movement of the motor 135 is not continuous:the motor 135 is controlled so as to obtain an alternating movement ofpredetermined amplitude, this movement being transmitted to the arm 131via a simple movement relay inside the carriage 130 (not shown). In thedrawing this type of alternating movement is symbolized by an arrow F2pointing both ways. We will agree to denote this movement control by theexpression “electric cam”. Preferably, not only does this movementchange direction, but its speed is varied continuously so as to obtainsuccessive positions of the characteristic points which will beexplained with reference to FIG. 2. Of course, the movements of thecarriage 130 and the arm 131 are synchronized.

[0025] The translation movement of the carriage 130, combined with themovement of the arm 131, are illustrated in FIG. 2. Respective possiblepositions a1, a2, a3, a4 and a5 of the center of rotation of the arm 131can be seen. Superposition of this transverse displacement on theintrinsic movement of the single-arm actuation mechanism (which is acircle: see patent application EP 1 231 049) gives the following overallmovement: the curve drawn as a broken line and passing through points(1), (2), (3), (4) and (5) represents the movement of the end 16 of thecord laying arm 131, outside which the cord 4 is reeled off.

[0026] As a variant, the movement of the carriage 130 could have beencontrolled by an electric cam. Thus, each of the two movements (that ofthe arm 131 and that of the carriage 130) could be controlled byrespective electric cams. As another variant, one or other of themovements of the arm 131 or carriage 130, or both of them, could becontrolled by a mechanical cam system designed to give the preferredsuccessive positions described in FIG. 2.

[0027] In FIG. 3 the actuation mechanism 3 is similar to that alreadydescribed in patent application EP 1 122 057. The cord laying element isan eyelet 6 mounted on an end arm 34. A main arm 31 is mounted on acarriage 301 by means of a front auxiliary arm 32 and a rear auxiliaryarm 33. The front auxiliary arm 32 is mounted on a spindle 320 and therear auxiliary arm 33 on a spindle 330. The end arm 34 inclines relativeto the main arm 31 so as to bring the eyelet 6 close to the bead of thefuture tire, even in the case when the building form is narrower at thelevel of the tire bead than half-way up the sidewall. The degree ofinclination, i.e. the approach towards the zone of the future tire bead,is carefully controlled in a manner whose details will be found by thereader in patent application EP 1 122 057 (not shown here, so as not toovercomplicate the drawing). The arms do not rotate continuously, butoscillate within the limits of an arc smaller than 360°, whose precisevalue depends on the exact constitution of the multiple-arm actuationmechanism 3 and on the application envisaged.

[0028] The carriage 301 is mounted and can slide on two parallel bars302. The carriage 301 comprises a foot 3010 in which a slot 3011 ishollowed out. The carriage 301 can move in alternation, guided by thebars 302, thanks to a motor 361 which controls a lever 362. The motor'srotation does not reverse, and this is symbolized in the drawing by aone-way arrow F3 (which does not exclude variable speed). At the end ofthe lever 362 is attached a lug 363 which is engaged in the slot 3011.

[0029] The movement of the multiple-arm actuation mechanism 3 iscontrolled by a motor 351 which drives the spindle 320 via a telescopicspindle 353. The spindle 330 is driven by the spindle 320 via a gearsystem arranged on the carriage 301 and designed so that the spindle 320can oscillate through an amplitude for example of about 2400. In thedrawing this type of alternating movement is symbolized by a two-wayarrow F4. In this embodiment as in the previous one, the movements canbe controlled in many different ways using mechanical or electric cams.

[0030] The translation movement of the carriage 301, combined with themovement of the multiple-arm actuation mechanism 3, are illustrated inFIG. 4. Respective positions x1, x2 and x3 are shown, which are thetrace of an imaginary plane connecting the geometrical axes of thespindles 320 and 330. The displacement of the carriage 301 causes adisplacement of the spindles 320 and 330, and hence a displacement ofthe centers of rotation of the front 32 and rear 33 auxiliary spindles.Superposition of this transverse displacement on the intrinsic movementof the multiple-arm actuation mechanism 3 as explained with the help ofFIG. 2, gives the following overall movements: the curve drawn with athick broken line passing through the points (1), (2), and (3)represents the movement of the eyelet 6; the curve drawn with a dot-dashline passing through the points a1, a2 and a3 represents the movement inspace of the axis 310, i.e. also the movement in space of the center ofrotation 31R of the main arm 31; finally, the curve passing through thepoints b1, b2 and b3 represents the movement in space of the lug 311.

[0031] The assembly constituting the actuation mechanism with arm(s) 3,whether with a single arm or with multiple arms, is fairly compact. Theassembly constituting the cord laying elements, namely the multiple-armactuation mechanism 3, and the control system for the carriage movementand the pressing elements 2, including the motor and the drivemechanism, form a sub-assembly that can easily be brought up to the corein an appropriate way and which can be moved out of the way, for exampleto allow other devices used for tire fabrication or for transferring thecore to other tire building positions, to be brought up to the core.

I claim:
 1. Device for the fabrication of a tire reinforcement, saiddevice being designed to fabricate a reinforcement made from a cord (4),said device comprising a frame and being designed for use in cooperationwith an essentially toroidal form which is mounted on the frame and ableto rotate about a rotation axis and on which said reinforcement isprogressively built up by laying arcs of said cord along a trajectorydesired for said cord on the surface of said form, said devicecomprising: a cord laying element through which the cord can slide; anactuation mechanism comprising at least one arm (131) on which said cordlaying element is mounted directly or indirectly, the actuationmechanism being designed to move said cord laying element in a cyclic,back and forth movement, bringing it in successive cycles close to eachof the ends desired for the cord in said trajectory; pressing elements(2G and 2D) near each end of said trajectory, to apply the cord onto theform at least at said ends; and wherein the actuation mechanism ismounted on the frame via a support which is itself mounted on means thatallow a degree of freedom relative to the frame which permits a parallelmovement relative to a plane tangent to a cylinder coaxial to therotation axis of the form.
 2. Device according to claim 1, in which saidmeans allowing a degree of freedom provide for a movement parallel tothe rotation axis of the form, this feature being not limiting the scopeof the invention.
 3. Device according to claim 1, in which the actuationmechanism comprises a single oscillating arm at whose end said cordlaying element is mounted.
 4. Device according to claim 1, in which theactuation mechanism comprises multiple arms.
 5. Device according toclaim 4, in which the actuation mechanism comprises a main arm mountedat the end of auxiliary arms.
 6. Device according to claim 5, in whichsaid cord laying element is mounted directly at the end of the main arm.7. Device according to claim 1, in which the cord laying element is aneyelet (6).
 8. Device according to claim 1, used with a motorizationsystem which controls in synchronism the rotation of the form, theactuation mechanism and the pressing elements, in which the motorizationsystem controls the movement of said support in synchronism.